Antenna-tuning apparatus



June 3, 1930. L. JONES ET AL 1,761,211

ANTENNA TUNING APPARATUS Filed Dec. 31, 1927 INVENTORS Leslev' L. Jones andJacOb Yolles AT TORNEYS Patented a... is; 1930 NITED STATES PAraNr orrlca marina L. mm, OI OBADELL, NEW JERSEY, AND JACOB YOLLES, OI BROOKLYN,

YORK, ASSIGNOBS TO TECHNIDYNE CORPOBATION,' OI NEW YORK, N. '12, A003- POBATIOI OF NEW YORK ANTENNA-TUNING APYARATUS Application filed December 81, 1927. Serial No. 243,789.

This invention relates to tuning equipment, for radio antennae, and has special reference to the provision of an improved tuning apparatus for antenna circuits in radio receiving equipment especially adapted for receiving the present band of broadcast frequencies.

, The prime desideratum of the present invention comprehends the provision of an improved apparatus for eflecting the tuning of the antenna of radio receiving circuits whereby antenna tuning overthe whole broadcast fr pli ed by simple and compact means operable with ease and convenience.

It has long been known that considerably more energy may be received from antenna stems when the antenna is series .tuned to t e frequency desired. The difiiculty of arranging for convenient and easily operated series tuning means has been, however largely instrumental in forcing the art to develop along other lines of producing simplified tuning equipment. The advantages of the 5 series tuning antenna are, however, considerable, and recently attempts have been made to introduce the same into the broadcast receiving equipment or apparatus, one such at tempt comprising the introduction or use of a variometer or variable inductance in series siderably as by the insertion of a series condenser and to increase the inductance so as to impart stifiness to the antenna. With such imposed constants the effect of poor msulation and dielectric loss is greatly reduced, 60 as is already well known in the art, but these eqpency band or range may be accom-- imposed constants inake necessary the use of a relatively high in-series inductance which is objectionable since the relatively large inductances orvariometers lack efliciency desirable for sharp tuning, particularly at the low wave len ths of the broadcast range.

We have 'scovered em irically that improved results over. thew ole broadcast receiving range may be secured "by employing dififerent inductance values for different parts of the wave length range and by relating the same to a tuning variable such as a tuning condenser so that one inductance value 1s associated with thetuningcondenser for one part of the range and another inductance value is associated therewith for a diiferent part of the wave length range, the construction and arrangement being such that efliciency forsharp tuning is obtainable, over the entire range; and a 'prlme object of our present invention comprehends the provision of an antenna tuning means for producing such improved results.

In the operation of such antenna tuning means it is highly desirable to minimize the number of control elements and to produce the tuning of the antenna for the whole wave length band by means of a single operated control element. It is a further prime object of our present invention, therefore, to so construct the tuning a aratus as to automatically associate the di erent inductance values wit-h the tuning condenser for the difierent sections of the wave length band.

To the accom lishment of the foregoing 55 and such other objects as will hereinafter appear, our invention consists in the elements and their relation one to the other, as hereinafter more particularly described and sought to be defined in the claims, reference being had to the accompanying drawings which show the preferred embodiment of our invention, and in which:

Fig. Us a wiring diagrammatic view show- 7 ing the antenna tuning apparatus of, our present invention associated with a tuned audion amplifier,

Fig. 2 is a diagrammatic view of a modification thereof, and

Fig. 3 is a view (end elevational and side elevational) of means for automatically associating the different inductance components of the antenna circuit with the tuning condenser.

Referring now more in detail to the drawings and having reference first to Fig. 1- thereof, we show the improved antenna circuit generally desi nated as A embodying our invention connected to a tuned or resonant audion circuit generally desi nated as B through a coupling condenser If, which preferably has an extremely small electrostatlc capacity of the order of 3 micro-microfarads, the audion amplifier circuit B comprising the audion or electron discharge tube 10, the inductance 11 and tuning condenser 12 arranged in a resonant circuit, these elements forming part of any conventional amplifier or selector system.

The antenna circuit A comprises the antenna proper a, the antenna inductance L and a variable condenser C arranged in series with the antenna and the ground connection g. To produce the desired improved results over the whole range, the inductance L is subdivided into at least two parts or sections L and L so that one inductance value is employable for one part of the range and another inductance value for another part of the ran e of received frequencies. In the form of t e invention shown in-Fig. 1 of the drawings, the inductance L is approximately one-third of the inductance L.

Both sections L and L. of the inductance L are associated with the same tuning condenser C; and in the preferred construction each of the inductancesections is associated with the tuning condenser C for the whole tuning range of the condenser. This is accomplished by the provision of a switch 8 tapped by means of the conductor 13 to the junction point of the inductances L and L and connected by means of the conductor 14 to the stator of the condenser C, the said switch being designed to selectively short circuit and close circuit the inductance section 7 L,. To maintain a simple control between the parts in associating each of the utilizable inductance sections with the entire tuning range of the condenser, the switch S is controlled by the rotor of the condenser O by a connection diagrammatically indicated by 15 in Fig. 1 of the drawings and described more in detail hereinafter in connection with Fig. 3 of the drawings so that during one-half of the rotation of the condenser G the antenna is tuned through the whole of the coil L and through the other half of the condenser G, the antenna is tuned through the smaller section L Referring now to Fig. 3 of the drawings, we show a preferred form of combined tuning condenser and switch for accomplishing the intended results, the switch S being arranged to be actuated by the condenser C at its maximum and minimum points. More specifically, the condenser C comprises a stator section 16 and a rotor section 17, and the switch S comprises a movable contact 18 which is insulated from the stator 16 and a fixed contact 19 which may be conductively connected to the stator 16, the movable contact 18 being provided in turn with an insulating button 20 projecting in the path of movement of the last plate 21 of the rotor assembly 17 as clearly shown in both views of Fig. 3 of the drawin s. From a consideration of these views it wilfiie seen that when the rotor 17 is rotated from the position shown in the direction of the full arrowed line for a range of one-half of the revolution, the button 20 will be en aged for closing the contacts of the switch this in turn short circuiting the inductance section L so that the entire tuning range of the condenser is then utilized in series with the inductance section L alone. It will be further seen that during the next half of the revolution or during the one-half of the revolution of the condenser C from the position shown in Fig. 3 in the direction indicated by the dotted arrowed line, the switch S will be open so that the entire inductance L is arranged in series with the condenser C for the complete tuning range of the latter.

In theuse of this tuning apparatus the o erator first tunes to any desired station by t e usual selector control found in tuned radio frequency sets such as the three condensers customarily employed in present day broadcast receivers, and then increases the signal pick-up with a concomitant increase of selectivity by a rotation of the antenna tuning condenser C. This antenna tuning condenser C is rotated by the operator through both halves of a revolution until the loudest signal is obtained, the different inductance values of the antenna being each automatically connected in circuit for the whole tuning range of the condenser C during such a complete or full revolution of the condenser rotor.

Referring now to Fig. 2 of the drawings wherein a modification of the invention is shown, the antenna circuit A comprises the inductances L and D forming separate coils, one utilizable for one part of the broadcast range and the other for the other part of the broadcast range in a manner similar to that described in connection with Fig. 1 of the drawings, these coils being controlled by a movable contact 18 engageable with either the contact 19 or 19, said contact 18 being also connectible to the tuning condenser G for automatic operation as indicated diagrammatically by the connection 15'. The remainder of the circuit arrangement is similar to that shown in Fig. 1 of the drawings, and is designated by similar reference characters.

The use and operation of our improved tuning apparatus or antennae and the many advantages thereof, both for producing im- ,able plate set, and stationaril proved operational results for the full freg uency band of present da broadcasting and or afi'ording a simplifie construction and convenient uni-control therefor will, in the main be fully apparent from the above detailed description thereof. It will be further apparent that while we have shown and described our invention in the preferred forms, many changes and modifications may be made in the structure disclosed without de arting fromthe spirit of the invention, defined in the following claims.

We claim:

1. An antenna tuning apparatus comprising an inductor and a continuously variable condenser serially arranged in an antenna circuit, the said mductor comprising a plurality of inductance sections and the said condenser including a continuously variable plate set, and means selectively connecting each of the said inductance sectlons with the said variable condenser, said means being automatically operated by engagement with one of the condenser plates of the variable condenser plate set.

2. An antenna tuning apparatus comprising an inductor and a continuously variable condenser serially arranged in an antenna circuit, the said lnductor com rising a plurality of inductance sections 0 difiierent values and the said condenser including a varimounted switch means selectively associatmg each of the said inductance sections with the said variable condenser, said switch means being automatically operated by engagement with the variable condenser plate set, whereby the inductance sections are automatically associated separately with the whole tuning range of the condenser over different parts of the frequency range.

3. An antenna tuning apparatus comprising a variable inductor composed of two inductance sections of different values and a continuously variable condenser having stator and rotor plate sets serially arranged in the antenna circuit; and a switch for said variable inductor positioned so as to be actuated by engagement of a plate of a rotor during rotation thereof, said switch being arranged to shift from either inductance section to the other after the condenser is Varied between its maximum and minimum points.

Signed at New York, in the county of New York and State of New York, this 21st day of December, A. D. 1927.

LESTER L. JONES. JACOB YOLLES. 

